/* Copyright (c) 2021 Xie Meiyi(xiemeiyi@hust.edu.cn) and OceanBase and/or its affiliates. All rights reserved.
miniob is licensed under Mulan PSL v2.
You can use this software according to the terms and conditions of the Mulan PSL v2.
You may obtain a copy of Mulan PSL v2 at:
         http://license.coscl.org.cn/MulanPSL2
THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
See the Mulan PSL v2 for more details. */

//
// Created by Wangyunlai on 2022/5/22.
//

#include "rc.h"
#include "common/log/log.h"
#include "common/lang/string.h"
#include "sql/stmt/filter_stmt.h"
#include "storage/common/db.h"
#include "storage/common/table.h"
#include <stdint.h>
#include <util/date.h>

FilterStmt::~FilterStmt()
{
  for (FilterUnit *unit : filter_units_) {
    delete unit;
  }
  filter_units_.clear();
}

RC FilterStmt::create(Db *db, Table *default_table, std::unordered_map<std::string, Table *> *tables,
		      const Condition *conditions, int condition_num,
		      FilterStmt *&stmt)
{
  RC rc = RC::SUCCESS;
  stmt = nullptr;
  // condition_num是filter语句中的条件数量
  // 对于每一个条件比较都要生成一个filter_unit
  // 所以需要在create_filter_unit这个函数里面去进行一些值的判断和转换

  FilterStmt *tmp_stmt = new FilterStmt();
  for (int i = 0; i < condition_num; i++) {
    FilterUnit *filter_unit = nullptr;
    rc = create_filter_unit(db, default_table, tables, conditions[i], filter_unit);
    if (rc != RC::SUCCESS) {
      delete tmp_stmt;
      LOG_WARN("failed to create filter unit. condition index=%d", i);
      return rc;
    }
    tmp_stmt->filter_units_.push_back(filter_unit);
  }

  stmt = tmp_stmt;
  return rc;
}

RC get_table_and_field(Db *db, Table *default_table, std::unordered_map<std::string, Table *> *tables,
		       const RelAttr &attr, Table *&table, const FieldMeta *&field)
{
  if (common::is_blank(attr.relation_name)) {
    table = default_table;
  } else if (nullptr != tables) {
    auto iter = tables->find(std::string(attr.relation_name));
    if (iter != tables->end()) {
      table = iter->second;
    }
  } else {
    table = db->find_table(attr.relation_name);
  }
  if (nullptr == table) {
    LOG_WARN("No such table: attr.relation_name: %s", attr.relation_name);
    return RC::SCHEMA_TABLE_NOT_EXIST;
  }

  field = table->table_meta().field(attr.attribute_name);
  if (nullptr == field) {
    LOG_WARN("no such field in table: table %s, field %s", table->name(), attr.attribute_name);
    table = nullptr;
    return RC::SCHEMA_FIELD_NOT_EXIST;
  }

  return RC::SUCCESS;
}

RC FilterStmt::create_filter_unit(Db *db, Table *default_table, std::unordered_map<std::string, Table *> *tables,
				  const Condition &condition, FilterUnit *&filter_unit)
{
  RC rc = RC::SUCCESS;
  
  CompOp comp = condition.comp;
  if (comp < EQUAL_TO || comp >= NO_OP) {
    LOG_WARN("invalid compare operator : %d", comp);
    return RC::INVALID_ARGUMENT;
  }

  Expression *left = nullptr;
  Expression *right = nullptr;
  if (condition.left_is_attr) {
    // 左边是字段
    Table *table = nullptr;
    const FieldMeta *field = nullptr;
    rc = get_table_and_field(db, default_table, tables, condition.left_attr, table, field);  
    if (rc != RC::SUCCESS) {
      LOG_WARN("cannot find attr");
      return rc;
    }
    left = new FieldExpr(table, field);
  } else {
    // 左边是值, 对该值进行判断与转化
    left = new ValueExpr(condition.left_value);
  }

  if (condition.right_is_attr) {
    if (comp == IS_NULL || comp == IS_NOT_NULL) {
      LOG_WARN("right value inis, is not condition can't be attribute");
      rc = RC::INVALID_ARGUMENT;
      return rc;
    }
    Table *table = nullptr;
    const FieldMeta *field = nullptr;
    rc = get_table_and_field(db, default_table, tables, condition.right_attr, table, field);  
    if (rc != RC::SUCCESS) {
      LOG_WARN("cannot find attr");
      delete left;
      return rc;
    }
    right = new FieldExpr(table, field);
  } else {
    if ((comp == IS_NULL || comp == IS_NOT_NULL) && condition.right_value.type != NULLS) {
      LOG_WARN("right value in is and is not condition must be null");
      rc = RC::INVALID_ARGUMENT;
      return rc;
    }
    // 假定日期输入至少满足格式要求,用来区分普通char和date
    int year,month,day;
    int ret = sscanf((char*)condition.right_value.data,"%d-%d-%d",&year,&month,&day);
    if(condition.right_value.type == CHARS && ret == 3){
      int32_t date = -1;
      RC rc = string2date((char*)condition.right_value.data,date);
      if(rc != RC::SUCCESS){
        return RC::INVALID_ARGUMENT;
      }
      value_destroy((Value *)&condition.right_value);
      value_init_date((Value *)&condition.right_value, date);
    }
    right = new ValueExpr(condition.right_value);
  }

  // if (condition.right_is_attr != 1 && condition.left_is_attr != 1)
  // {
  //  left = new ValueExpr(condition.left_value);
  //  right = new ValueExpr(condition.right_value);
  // }

  filter_unit = new FilterUnit;
  filter_unit->set_comp(comp);
  filter_unit->set_left(left);
  filter_unit->set_right(right);
  // 检查两个类型是否能够比较
  return rc;
}
